Unknown metrics

[spaghettifunk]

From the feeds received from Apache Druid there are a bunch of metrics that are not described in the documentation

"sys/fs/files/count":
"sys/fs/files/free":
"sys/mem/actual/used":
"sys/mem/actual/free":
"sys/net/write/dropped":
"sys/net/read/overruns":
"sys/net/write/errors":
"sys/net/read/packets":
"sys/net/read/errors":
"sys/net/write/collisions":
"sys/net/write/packets":
"sys/net/read/dropped":
"sys/net/read/frame":
"sys/net/write/overruns":
"sys/tcp/attemptFails":
"sys/tcp/retrans/segs":
"sys/tcp/in/segs":
"sys/tcp/out/rsts":
"sys/tcp/passiveOpens":
"sys/tcp/out/segs":
"sys/tcp/activeOpens":
"sys/tcp/estabResets":
"sys/tcp/in/errs":
"sys/net/inbound":
"sys/net/outbound":
"sys/tcp/inbound":
"sys/tcp/outbound":
"sys/tcp/state/established":
"sys/tcp/state/synSent":
"sys/tcp/state/synRecv":
"sys/tcp/state/timeWait":
"sys/tcp/state/close":
"query/cache/caffeine/delta/requests":
"query/cache/caffeine/total/requests":
"query/cache/caffeine/delta/loadTime":
"query/cache/caffeine/total/loadTime":
"query/cache/caffeine/delta/evictionBytes":
"query/cache/caffeine/total/evictionBytes":
"compact/task/count"
"emitter/events/emitted/delta"
"emitter/buffers/dropped/delta"
"emitter/buffers/allocated/delta"
"emitter/buffers/failed/delta"
"emitter/batchFilling/timeMsSum"
"emitter/batchFilling/count"
"emitter/batchFilling/maxTimeMs"
"emitter/batchFilling/minTimeMs"
"emitter/events/emitQueue"
"emitter/events/large/emitQueue"
"emitter/buffers/emitQueue"
"emitter/buffers/reuseQueue"

If there is a description somewhere we can implement these metrics as well